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MC33065-L View Datasheet(PDF) - Motorola => Freescale

Part Name
Description
Manufacturer
MC33065-L Datasheet PDF : 14 Pages
1 2 3 4 5 6 7 8 9 10 Next Last
MC34065–H, L MC33065–H, L
Undervoltage Lockout
Two Undervoltage Lockout comparators have been
incorporated to guarantee that the IC is fully functional before
the output stages are enabled. The positive power supply
terminal (VCC) and the reference output (Vref) are each
monitored by separate comparators. Each has built–in
hysteresis to prevent erratic output behavior as their
respective thresholds are crossed. The VCC comparator
upper and lower thresholds are 14 V/10 V for –H suffix, and
8.4 V/7.6 V for –L suffix. The Vref comparator upper and lower
thresholds are 3.6 V/3.4 V respectively. The large hysteresis
and low startup current of the –H suffix version makes it
ideally suited in off–line converter applications where efficient
bootstrap startup techniques are required (Figure 28). The –L
suffix version is intended for lower voltage dc–to–dc
converter applications. The minimum operating voltage for
the –H suffix is 11 V and 8.2 V for the –L suffix.
Drive Outputs and Drive Ground
Each section contains a single totem–pole output stage
that is specifically designed for direct drive of power
MOSFETs. The Drive Outputs are capable of up to ±400 mA
peak current with a typical rise and fall time of 50 ns with a
1.0 nF load. Additional internal circuitry has been added to
keep the outputs in a sinking mode whenever an
Undervoltage Lockout is active. This characteristic eliminates
the need for an external pull–down resistor. The totem–pole
output has been optimized to minimize cross–conduction
current in high speed operation. The addition of two 10
resistors, one in series with the source output transistor and
one in series with the sink output transistor, reduces the
cross–conduction current to minimal levels, as shown in
Figure 13.
Although the Drive Outputs were optimized for MOSFETs,
they can easily supply the negative base current required by
bipolar NPN transistors for enhanced turn–off (Figure 25).
Figure 15. Representative Block Diagram
VCC 16
Vin = 15V
Vref
15
2.5V
R
R
Internal
Bias
Reference
Regulator
+
+
VCC
+
UVLO
Sync Input
1
20k
+
Vref
3.6V
UVLO
10
3
RT
CT
2
Voltage Feedback 1
4
Compensation 1
5
Oscillator
+
Error
Amp 1
1.0mA
2R
1.0V
Vref
Current Sense
Comparator 1
+
R
PWM
Latch 1
S
Q
R
Drive Output 1
Q1
10
7
Current Sense 1
6
RS
250µA
10
Drive Output 2
Q2
Enable Input
14
PWM
Latch 2
10
10
1.0mA
Current Sense
S
Voltage Feedback 2
13
+
Error
Amp 2
2R
Comparator 2
+
1.0V
R
RQ
R
Current Sense 2
11
Compensation 2
12
RS
Gnd 8
Drive Gnd 9
+
=
Sink Only
Positive True Logic
MOTOROLA ANALOG IC DEVICE DATA
7
 

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